AVS 49th International Symposium
    Manufacturing Science and Technology Monday Sessions
       Session MS+SE-MoM

Paper MS+SE-MoM10
In-Situ Studies of the Amorphous to Microcrystalline Transition of Hot-Wire CVD Si:H Films Using Real-Time Spectroscopic Ellipsometry

Monday, November 4, 2002, 11:20 am, Room C-109

Session: In-Situ Monitoring and Metrology for Coating Growth and Manufacturing
Presenter: D.H. Levi, National Renewable Energy Laboratory
Authors: D.H. Levi, National Renewable Energy Laboratory
B.P. Nelson, National Renewable Energy Laboratory
J.D. Perkins, National Renewable Energy Laboratory
Correspondent: Click to Email
In-situ real-time spectroscopic ellipsometry (RTSE) provides detailed information on the evolution of the structural and optical properties of Si:H films during growth.@footnote 1@ We have used in-situ RTSE to characterize the morphology and crystallinity of hot-wire CVD (HWCVD) Si:H films as a function of substrate temperature T@sub s@, hydrogen dilution R=[H]/[H+SiH@sub 4@], and film thickness d@sub b@. Transitions from one mode of film growth to another are indicated by abrupt changes in the magnitude of the surface roughness during film growth. The degree of crystallinity of the film can be determined from the bulk dielectric function. We have studied the growth parameter space consisting of R from 0 to 14, T@sub s@ from 250@super o@C to 550@super o@C, and d@sub b@ from 0 to 1 µm. For each set of R and T@sub s@ values, the structural evolution of the film can be characterized by the shape of the surface roughness thickness d@sub s@ versus bulk thickness d@sub b@ curve. In contrast to studies done by Collins et al on PECVD growth of Si:H films, our studies of HWCVD growth find no conditions where d@sub s@ remains constant after coalescence of the initial nucleation centers. Most of the films grown within the range of parameters studied exhibit a secondary nucleation and coalescence signature. The transition between a-Si:H and uc-Si:H growth is near the R=3 to R=4 dividing line. Initial coalescence of purely uc-Si:H material does not occur until R>8. We have verified the RTSE crystallinity classification using ex-situ Raman scattering. @FootnoteText@ @footnote 1@ R.W. Collins, Joohyun Koh, H. Fujiwara, P.I. Rovira, A.S. Ferlauto, J.A. Zapien, C.R. Wronski, R. Messier, Appl. Surf. Sci., 154-155, 217-228 (2000).